The present invention relates to a device for and a method of connecting roll films to each other, for example, for use in liquid filling machines as a closure material.
As disclosed in JP-A 53-11694 (1978), a device of the type mentioned is already known which comprises means for transporting a preceding film and a film following the film via a joining station, a pair of joining members arranged at the joining station on respective opposite sides of a film transport path, a pair of cutters positioned upstream from the joining members with respect to the direction of transport of the film and arranged on respective opposite sides of the film transport path so as to be movable toward or away from each other, and a cutter receiver fixedly disposed between the cutters. The following film is joined to the preceding film by the joining members, and the portion of the preceding film remaining is cut off by the cutters.
The films joined by the conventional device have a lap at the joint, and a length of the preceding film corresponding to the distance of the cutters from the connecting members extends from the joint as an unnecessary portion. The lap and the unnecessary portion not only result in a waste of film but are likely to bite into the device.
JP-A 5-97122 (1993) discloses a roll film connecting device which comprises means for transporting a preceding film and a film following the film via a connecting station, a pair of connecting members arranged at the connecting station and movable toward or away from each other with a film transport path positioned therebetween, each of the connecting members having a face opposed to the other and serving as a suction face, and actuating means for moving the connecting members toward each other upon detecting the rear end of the preceding film as brought nearly to the space between the connecting members. A connecting tape is affixed to the leading end of the following film so as to partly extend downstream beyond the leading end with respect to the direction of transport of the tape, and the partly extending portion of the connecting tape is caused to be attracted to the corresponding connecting member by suction.
With this conventional device, the accuracy of the joint of the two films is dependent on the timing of moving the two connecting members toward each other. If this timing is too early, the two films lap over each other, whereas if the timing is too late, a clearance will occur between the two films. Thus it is difficult to connect the two films together accurately end-to-end. If it is attempted to position the films accurately relative to each other, the control mechanism therefor tends to become complex.
An object of the present invention is to overcome the foregoing problems and to provide a device for and a method of connecting roll films, by which the rear end of the preceding film can be connected to the leading end of the following film accurately by a simple construction.
The present invention provides a roll film connecting device comprising means for transporting a preceding film and a film following the film via a connecting station, a pair of connecting members arranged at the connecting station and movable toward or away from each other with a film transport path positioned therebetween, each of the connecting members having a face opposed to the other and serving as a suction face, a pair of cutters so arranged as to be movable out of or into the respective suction faces of the connecting members, and a cutter receiver so disposed as to be movable into or out of a space between the connecting members as moved away from each other.
With the roll film connecting device of the present invention, the cutter receiver is advanced into the space between the pair of connecting members, and the preceding film is cut by the cutter as projected from the suction face of the corresponding connecting member and by the cutter receiver. The two films are connected together by the connecting members, with the cutter receiver retracted from the space between the connecting members. Since the preceding film is cut and connected to the following film at one location, the films can be positioned easily relative to each other, with the result that the rear end of the preceding film can be connected to the leading end of the following film with high accuracy.
When each of the connecting members comprises a pair of vacuum pipes arranged at respective opposite sides of the cutter and each having suction holes formed in a suction face thereof, the cutter can be easily moved out of or into the suction face of the connecting member by a simple construction.
When each of the connecting members is attached to a movable frame along with the cutter, the connecting member and the cutter can be moved together. This also serves to give improved accuracy to the connection.
Further when a fluid pressure cylinder is provided between the cutter and the movable frame, the cutter is movable independently of the movement of the connecting member and can therefore be operated at desired timing.
In connecting the following film to the preceding film by the roll film connecting device described, a connecting tape is affixed to the leading end of the following film so as to partly extend downstream beyond the leading end with respect to the direction of transport of the tape, and the partly extending portion of the connecting tape is caused to be attracted to the corresponding connecting member by suction, whereby the rear end of the preceding film can be connected to the leading end of the following film in the manner of a butt joint.